This invention relates to the polymerization or copolymerization of ethylene and/or .alpha.-olefins. More particularly, the invention relates to newly-developed, highly active catalysts prepared by a novel activation treatment of the titanium trichloride component of conventional catalysts for polymerization, including copolymerization, of ethylene or .alpha.-olefins using the complex catalysts of titanium trichloride and organometallic compounds. As used herein, the term "polymerization" includes copolymerization as well as the homopolymerization of .alpha.-olefins.
The polymerization of ethylene and .alpha.-olefins to solid polymers employing catalyst systems containing a transition metalhalide, such as titanium trichloride or titanium tetrachloride, an organometallic compound, and other organic compounds, such as amines, ethers and thioethers is well known.
A complex transition metal halide of an aluminum reduced titanium trichloride having the empirical formula 3TiCl.sub.3 AlCl.sub.3 provides the best results in the polymerization of ethylene, .alpha.-olefins and especially propylene. Usually the organometallic compound is a trialkyl aluminum or dialkyl aluminum monohalide.
However, the polymerization of .alpha.-olefins using these catalysts has the following defects: (1) trialkyl aluminum as organometallic compound has a high activity; but; yields a substantial amount of amorphous polymer; (2) dialkylaluminum monohalide reduces the yield of amorphous polymer but the rate of polymerization is slow. Therefore, a highly active catalytic system, which selectively increases the yield of crystalline polymer over that of amorphous polymer is in demand.